START UP CONDITIONS
Whenever the water heater is ﬁ lled with cold water, some condensate
will form while the burner is on. A water heater may appear to be leaking
when in fact the water is condensate. This usually happens when:
a. A new water heater is ﬁ lled with cold water for the ﬁ rst time.
b. Burning gas produces water vapor in water heaters, particularly high
efﬁ ciency models where ﬂ ue temperatures are lower.
c. Large amounts of hot water are used in a short time and the reﬁ ll
water in the tank is very cold.
Moisture from the products of combustion condense on the cooler tank
surfaces and form drops of water which may fall onto the burner or other
hot surfaces to produce a "sizzling" or "frying" noise.
Because of the suddenness and amount of water, condensate water
may be diagnosed as a "tank leak". After the water in the tank warms
up (about 1-2 hours), the condition should disappear.
Do not assume the water heater is leaking until there has been enough
time for the water in the tank to warm up.
An undersized water heater will cause more condensation. The water
heater must be sized properly to meet the family's demands for hot water
including dishwashers, washing machines and shower heads.
Excessive condensate may be noticed during the winter and early spring
months when incoming water temperatures are at their lowest.
Good venting is essential for a gas ﬁ red water heater to operate properly
as well as to carry away products of combustion and water vapor.
It is not uncommon to experience a small amount of smoke and odor
during the initial start-up. This is due to burning off of oil from metal parts,
and will disappear in a short while.
Water supply systems may, because of such events as high line
pressure, frequent cut-offs, the effects of water hammer among others,
have installed devices such as pressure reducing valves, check valves,
back ﬂ ow preventers, etc. to control these types of problems. When
these devices are not equipped with an internal by-pass, and no other
measures are taken, the devices cause the water system to be closed.
As water is heated, it expands (thermal expansion) and closed systems
do not allow for the expansion of heated water.
The water within the water tank expands as it is heated and increases
the pressure of the water system. If the relieving point of the water
heater's temperature-pressure relief valve is reached, the valve will
release the excess pressure. The temperature-pressure relief valve
is not intended for the constant relief of thermal expansion. This is
an unacceptable condition and must be corrected. It is recommended
that any devices installed which could create a closed system have a
by-pass and/or the system have an expansion tank or device to relieve
the pressure built by thermal expansion in the water system. Expansion
tanks are available through Sears stores and Sears Service Centers.
Contact Sears Service Center for assistance in controlling these
situations, see Figure 27.
FOR YOUR INFORMATION
Thermal Expansion Tank Speciﬁ cations
8 (203 mm) 12-3/4 (323 mm) 3/4" Male
11 (279 mm) 14-3/4 (375 mm) 3/4" Male
Expansion Tank Sizing Chart
*Highest recorded inlet water pressure in a 24 hour period or regulated
NOTE: Expansion tanks are pre-charged with a 40 psi air charge. If
the inlet water pressure is higher than 40 psi, the expansion tank's
air pressure must be adjusted to match that pressure, but must not
be higher than 80 psi.
Water Heater Capacity (Gallons)